How do I add a dynamic press release and industry news area to my site design?

I am a graphic designer who is recently adding "web designer" to my skill set. I have been tasked with, and mostly completed redesigning my company's web site. Here is a better explanation of what I want to do:
Two other people in my organization will be contributing content for our site on a regular basis, and they are NOT web designers. They will need to post press releases pertaining to our organization, and post industry news related articles.
I have designed areas on the home page where the top 5 or so most recent stories/press releases will appear, with just a title and "read more" link to a page with the full article.

At the moment, we are doing this manually because I don't know how to have it be more automated. For example, they write their article or press release, create a page for it, it then gets added to the full list of articles or press releases, and finally, the "top 5" blocks on the home page dynamically update.
All of this would happen without need for my help.

I have created the site with Dreamweaver CS5 and we have Contribute for the purpose of other people in the company updating their own respective areas ongoing.

But this one simple task perplexes me! I know lots of sites do it, I just haven't had any luck so far in searching for the technique.

Today we launched the brand new site I redesigned which you can view

If anyone could point me in the right direction in how I can do the above tasks, I'd be ever so grateful! And please explain fully, as I am still learning this web development stuff.

Thanks in advance!